Study of heterogeneous reaction of dimethyl sulfide on atmospheric-like particulate TiO₂

Dimethyl sulfide (DMS) related to solar radiation and greenhouse effect is one of the most important volatile sulfides and its' oxidation products are also important contributors to acid rain. It is of great importance to study the consumption and reactions of DMS in the atmosphere. In this work, atmospheric-like particulate TiO₂ was selected to study the reaction mechanism of DMS on TiO₂ with the purpose to explore the possible heterogeneous oxidation of DMS. The results showed that the heterogeneous reaction of DMS with TiO₂ occurred under the condition of illumination, which is a first-order-like reaction with the rate constant K = 2.83 × 10^-4/s, the initial reaction uptake coefficient and the steady reaction uptake coefficient indicated the occupation of products and by-products on the surface of TiO₂. The heterogeneous reaction mechanism of DMS studied by aerosol time-of-flight mass spectrometry (ATOFMS) suggested that DMS underwent a series of complex chemical reactions with sulfate and various sulfur-containing gas products, in which hydroxyl radicals might play an important role.